Last July my brother and I bought a Beneteau First 345 1984 with an Yanmar 2GM engine. The boat developed a squeal shortly after taking possession of the vessel. First thing we did was check the transmission fluid level. The fluid level was a little low, added transmission fluid. Could still hear the squeal. Played around with throttle settings and found that when the engine was under full load the squeal was gone. As the boat would approach hull speed, squeal would return. When we where idling along, there was also no squeal. Very puzzling, tried to locate the source of the squeal, using screwdriver on the ear, could not locate a source for the squeal. Decided after talking to a couple of yard operators I know, that it is probably a bad cutlass bearing. This spring we had planed to haul out to change the cutlass bearing, repack the shaft log, change the prop and install a couple of thru-hulls. But the haul out is a different long story. I’ll tell it later. The short version of the story is that we replace the cutlass bearing, repack the shaft log, and we still have the squeal. Next we align the engine, still have the squeal. Following weekend we adjust the shift lever travel, still squeals. Well we are very frustrated and shaking are heads. A customer of mine who use to run a boatyard, tells me that they use to get a squeal like I had explained to him from the propeller. So we decide to install the new Martec folding propeller, guess what, the squeal is gone. I'll post the haul-out story later.